This application for a Research Career Development Award (RCDA) reflects both the candidate's long-time interest in the effects of environmental exposures on adverse health outcomes and a specific change in career interest from one mainly of cancer epidemiology to one primarily of reproductive epidemiology The RCDA will provide the candidate the opportunity to acquire skills and knowledge in laboratory techniques and physiology in reproductive endocrinology, conducting prospective studies using 6-month diaries, biological markers of outcomes and exposures, and statistical analysis of these data. The knowledge gained will have preventive implications in meeting the challenge of identifying women at high risk for adverse reproductive outcomes and abnormal ovarian function. Long-term goals include developing clinical epidemiologic studies of ovarian function and epidemiologic studies to examine the effects of ergonomic stressors, physical activity, stress, ethnicity and environmental exposures on ovarian function, using biologic assays of reproductive urinary steroid hormones, and testing the validity of further refined urine screening assays of human chorionic gonadotropin (hCG). The RCDA will thus involve biochemical epidemiology, linking epidemiologic study data with laboratory investigations, thus enhancing the quality and biologic significance of the epidemiologic findings of these studies. The candidate is a co-investigator for a prospective study to follow 500 eligible women employed full-time in wafer-manufacturing jobs in the semiconductor industry for 6 of their menstrual cycles. Women will collect daily morning urine samples and complete a brief daily diary, covering key points related to their menstrual cycle, daily habits and exposures at work. A detailed telephone interview will be administered to determine any changes in habits or status. An exit questionnaire will also be administrated after 6 cycles. All pregnancies and pregnancy losses will be determined by urine assays for hCG. Outcomes of pregnancies that are not spontaneously or therapeutically aborted will be determined by contacting the women who become pregnant after their expected date of delivery. Data will be analyzed to determine if certain chemical, physical or ergonomic exposures in wafer-manufacturing are associated with an increased risk of spontaneous abortion or other adverse reproductive outcomes.